Transfersomes for transdermal drug delivery

Transfersomes^® (Idea AG) are a form of elastic or deformable vesicle, which were first introduced in the early 1990s. Elasticity is generated by incorporation of an edge activator in the lipid bilayer structure. The original composition of these vesicles was soya phosphatidyl choline incorporating sodium cholate and a small concentration of ethanol. Transfersomes are applied in a non-occluded method to the skin and have been shown to permeate through the stratum corneum lipid lamellar regions as a result of the hydration or osmotic force in the skin. They have been used as drug carriers for a range of small molecules, peptides, proteins and vaccines, both in vitro and in vivo. It has been claimed by Idea AG that intact Transfersomes penetrate through the stratum corneum and the underlying viable skin into the blood circulation. However, this has not been substantiated by other research groups who have extensively probed the mechanism of penetration and interaction of elastic vesicles in the skin. Structural changes in the stratum corneum have been identified, and intact elastic vesicles visualised within the stratum corneum lipid lamellar regions, but no intact vesicles have been ascertained in the viable tissues. Using the principle of incorporating an edge-activator agent into a bilayer structure, a number of other elastic vesicle compositions have been evaluated. This review describes the research into the development and evaluation of Transfersomes and elastic vesicles as topical and transdermal delivery systems.